Geometrical error improvement of Aramid honeycomb workpieces in robot-based triangular knife ultrasonic cutting process

Due to the notable advantages of ultrasonic-assisted machining, this technology is being more and more adopted in different manufacturing processes. Aramid honeycomb structures are among materials for which ultrasonic-assisted machining has become an interesting alternative thanks to its effect in reduction of machining forces and less micro imperfections. A considerable number of research works have addressed micro machining defeats in ultrasonic application such as dust generation and fiber delamination in Aramid honeycomb workpieces. However, in this study, a great attention is dedicated to the geometrical errors observed in the workpieces in cutting process of Aramid honeycomb structures using ultrasonic technology. The effect of different elements involved in robotic-based ultrasonic-assisted cutting process of Aramid honeycomb structures on these error types has been studied. To proceed this goal, a machining force estimation model is experimentally developed using the machining forces captured during the execution of several cutting tests. An on-site measurement process for measuring the geometrical errors in resulted workpieces is presented. The compliance behavior of robot-tool system is simulated using an extended virtual joint method (VJM) approach. In this approach, the machining tool is considered an additional joint-link system attached to the 6-revolute joint industrial system. Simulation results based on this method applied on the case study showed that the portion of contribution of industrial robotic arm to the compliant errors of process is negligible compared with the one of ultrasonic cutting knife. An offline compensation algorithm is proposed based on the developed machining force and tool compliance behavior models. Experimental results supported the efficiency of the proposed compensation method in reducing the geometrical error by up to 95% based on the machining features.